Zhong C, Wang L, Hu S, Huang C, Xia Z, Liao J, Yi W, Chen J. Poly(I:C) enhances the efficacy of
phagocytosis checkpoint blockade immunotherapy by inducing IL-6 production.
J Leukoc Biol 2021;
110:1197-1208. [PMID:
33988261 DOI:
10.1002/jlb.5ma0421-013r]
[Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/16/2021] [Accepted: 04/27/2021] [Indexed: 01/19/2023] Open
Abstract
Macrophage phagocytosis plays essential roles in antitumor immunity. CD47/SIRPα phagocytosis checkpoint blockade has demonstrated therapeutic potential in several hematopoietic cancers, but recent clinical studies reported very limited efficacy against solid malignancies. Here, we show that polyinosinic-polycytidylic acid (Poly(I:C)), a synthetic analog of double-stranded RNA, enhances the antitumor activity of CD47 blockade in colorectal cancer in vitro and in vivo. Poly(I:C) activation leads to a potent immune response characterized by the production of proinflammatory cytokines, especially IL-6. Stimulation with IL-6 promotes the PI3K signaling and cytoskeletal reorganization required for macrophage phagocytosis mediated by CD47 blockade. Our findings demonstrate the potential of Poly(I:C) to synergize the efficacy of CD47 blockade therapy and a novel role for IL-6 in macrophage phagocytosis, which provide new strategy for combinational cancer immunotherapy.
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